“You’d have to ask Dom Clément,” said the abbot. “He designed the abbey. He put in the garden and the hidden Chapter House and everything else. He was a master architect you know. Renowned in his time. You can see his brilliance.”

Gamache nodded. He could. And brilliance was exactly the right word. Not only in the simple, elegant lines, but in the placement of the windows.

Every stone was there for a reason. Nothing superfluous. Nothing ornate. All had a reason for being. And there was a reason the abbot’s garden was private, if not secret.

Gamache turned back to Frère Simon. “If no one else used the garden, why did you think one of the monks might stumble across the body of Frère Mathieu?”

“I hadn’t expected to find the prior there,” said Simon. “I didn’t know what else to expect.”

There was silence then, as Gamache studied the guarded monk.

Then the Chief nodded and turned back to the abbot.

“We were talking about the sheet of paper found on the body of the prior. You think the paper’s old, but the writing isn’t. Why do you say that?”

The two men returned to their chairs, while Frère Simon hovered in the background, tidying, shifting papers. Watching. Listening.

“The ink’s too dark, for one thing,” said Dom Philippe, as they studied the page. “Vellum soaks up liquid, over time, so that what’s left on the surface isn’t really ink anymore, but a stain, in the shape of the words. You can see that in the plan of the monastery.”

Gamache leaned over the scroll. The abbot was right. He’d thought with the passage of time and exposure to the sun the black ink had faded slightly, but it hadn’t. It had been absorbed into the vellum. The color was now trapped inside the page, not resting on top.

“But that,” the abbot waved to the yellowed paper, “hasn’t sunk in yet.”

Gamache frowned, impressed. He’d still consult a forensics expert, but he suspected the abbot might be right. The yellowed chant wasn’t old at all, just made to look that way. Made to deceive.

“Who would have done this?” Gamache asked.

“I can’t know.”

“Let me rephrase that, then. Who could have done this? I can tell you, not many people can sing a Gregorian chant, never mind write one, even a mockery of one, using these.”

He placed his index finger firmly over one of the neumes.

“We live in different realities, Chief Inspector. What’s obvious to you, isn’t to me.”

He left and returned a moment later with a workbook, clearly modern, and opened it. Inside, on the left page, were Latin text and the squiggled neumes. On the right was the same text, but this time instead of neumes there were musical notes.

“This is the same chant,” Dom Philippe explained. “One side’s in the old form, with neumes, and the other’s in modern notes.”

“Who did this?”

“I did. An early attempt to transcribe the old chants. Not very good, or accurate, I’m afraid. The later ones are better.”

“Where did you get the old chant?” Gamache pointed to the neume side.

“From our Book of Chants. Before you get excited, Chief Inspector—”

Yet again Gamache realized even slight shifts in his expression were readable by these monks. And a tiny ripple of interest was considered “excited” in this placid place.

“—let me tell you that many monasteries have at least one, often many books, of chants. Ours is among the least interesting. No illuminated script. No illustrations. Pretty dull, by church standards. All the impoverished Gilbertines could afford at the time, I suspect.”

“Where’s your Book of Chants kept?”

Was this the treasure? Gamache wondered. Kept hidden. Was one monk assigned to guard it? Perhaps even the dead prior. How powerful would that make Frère Mathieu?

“It’s kept on a lectern in the Blessed Chapel,” said the abbot. “It’s a huge book, left open. Though I think Frère Luc has it now in the porterie. Studying it.”

The abbot gave an infinitesimal smile. He could see the slight disappointment on the Chief’s face.

It was disconcerting, Gamache realized, to be so easily read. It also took away any assumed advantage an investigator had. That suspects didn’t know what the police were thinking. But it seemed this abbot knew, or could guess, just about everything.

Though Dom Philippe wasn’t all-seeing, all-knowing. After all, he hadn’t known he had a murderer among them. Or perhaps he had.